After all these years, Sam Shepard finally looks like the kind of iconic cowpoke he's always idolized, his features having completed the trip from ruggedly handsome to tired and leathery. As an actor, playwright and screenwriter, he's been traveling down the same dusty metaphoric trail for decades, forever chasing the myth of the American frontier. He's still patrolling the range, but as the star and writer of Don't Come Knocking, he's about as authentic as the Marlboro Man. He has again teamed up with oddball director Wim Wenders for a lukewarm reworking of the themes featured in their far more effective original collaboration, 1984's Paris, Texas.

In Knocking, Shepard stars as Howard Spence, a faded matinee idol with a résumé like Randolph Scott's and a rap sheet like Russell Crowe's. Finding himself in a midlife crisis, he goes AWOL from the set of his latest picture. After stealing a horse and hopping on a bus, Howard finds his way to his mother's (Eva Marie Saint) house, a spot he's avoided for nearly 30 years. Mom seems unfazed by the return of her prodigal movie star, and offers him breakfast, his late father's pristine old Packard and a tip about the son he fathered long ago while on location in Montana. After a bit of carousing and ambling, Spence heads to Butte and locates old flame Doreen (Shepard's real-life former flame Jessica Lange), who is waiting tables in the same dingy café where their son (Gabriel Mann) dons a smoking jacket and warbles gloomy hipster ballads at night with his punky disaster of a girlfriend (Fairuza Balk). This cozy little family reunion is disrupted by two characters in pursuit of Howard: Sky (Sarah Polley), a young woman carrying around a big secret along with her mother's ashes in a blue vase; and a relentless bond-company agent played with scene-stealing energy by Tim Roth.

Polley makes the most of her screen time, though she's seldom asked to do more than look lovely and winsome. Though there are a few great moments from the supporting players, they can't compensate for the emotional doughnut at the center of the story: a selfish, inarticulate lump where a leading man should be. Though he's supposed to be an aging Lothario, Shepard's Howard comes across as a grizzled old coot, with neither the charisma nor sympathy to keep you rooting for him as he struggles to figure it all out. And the storytelling is undercut by some fruitless improvisation and dialogue that's as flat as the prairie. Wenders knows how to make beautiful imagery, but his deep affection for sagebrush kitsch gets in the way of narrative. It seems he's bought into the counterfeit romance of vanishing heroes and lonesome barrooms that Shepard is so eager to peddle.